Rotating radiator screens are well known in the art. They are used to filter debris from an ambient air stream as it is drawn into the engine compartment of a work machine such as a combine harvester for cooling and other purposes. Typically, materials filtered from the airstream cling to the outside of the rotating screen until passing a “dead spot” that blocks incoming flow and causes the materials to lose their adhesion to the screen and drop off.
In spite of the long history of rotating radiator screens and a variety of improvements over the years, there still remains a problem in reliably sealing the interface between the rotating screen and the sidewall or other wall surface of the machine to prevent materials from being sucked into the machine without first passing through the screen itself. Various of kinds of mechanical seals have been tried over the years, including resilient skirts and the like, but none has been totally satisfactory for a number of reasons.
Accordingly, an important object of the present invention is to provide an improved dynamic sealing arrangement at the interface between the rotating screen and the adjacent wall surface so that debris-laden ambient air is discouraged from entering the machine through the interface and is instead forced to enter through the screen itself and be subjected to the filtering action that the screen provides. To this end, instead of attempting to block the entry of ambient air by mechanical or physical means at the interface, the present invention relies upon the creation of positive pressure in the region of the interface instead of suction pressure so as to repel the ambient air and the foreign materials carried thereby. In effect, a type of outflowing “air curtain” is created at the interface that moves in a generally axial direction at that location to prevent the ingress of ambient air to the interior of the machine without first passing through the filter surfaces of the screen.